The present invention relates generally to a method and system for predicting fuel consumption rates in a residential structure. More specifically, the present invention provides a method and system for more accurately determining the amount of fuel required to maintain a residential structure at a consistent temperature, thereby allowing identification of various system anomalies that may occur over time.
It is well known in the prior art that the fuel usage required for the maintenance of a constant temperature in a residential structure is an inverse function relative to the changes in the ambient outdoor temperature. In the most simplistic terms, as the ambient outdoor temperature decreases, the fuel consumption required to maintain the interior of the residential structure at a consistent temperature increases. Since this relationship can be calculated, home heating fuel suppliers such as fuel oil and propane companies have developed formulas and systems to predict the rate at which a residential building will consume fuel. This calculation then lets the fuel supplier schedule automatic deliveries to replenish the fuel storage tanks before they are empty. Typically these formulas rely first on the calculation of heating degree-days, which are generally defined as 65° F. minus the average daily temperature and then on the calculation of the fuel usage of a particular structure per heating degree day. Therefore, in order to accurately predict the fuel usage of the structures that they service, the fuel suppliers collect information on outdoor air temperature that is in turn used to calculate the heating degree-days. For example, if the average outside temperature for the day is 28° F., then the number of heating degree-days for that day is 65°-28° or 37 heating degree-days.
As stated above, once the heating degree-days are known, the second factor in the fuel consumption rate is the rate at which a given structure consumes fuel per heating degree-day. The consumption rate relative to the total number of heating degree-days is typically determined based on historical observation. In these calculations, the fuel consumption or burn rate is referred to as a K factor and is defined as heating degree-days per unit of fuel. Once a supplier has knowledge of the heating degree-days and the K factor of the residential structure, fuel suppliers can estimate when fuel deliveries are needed by evaluating the remaining fuel in the tank as heating degree days accumulate during the heating season. Typically, fuel deliveries are scheduled based on tracking simple heating degree-days, which reflect how much heating is required based on outdoor air temperature. As the outdoor temperature drops, heating degree-days increase and more fuel is used.
It is of note that this system can also be used historically to track changes in fuel burn rates relative to weather conditions in order to determine anomalies in the residential heating pattern. For example, a historic review of the fuel usage relative to heating degree-days can provide information that indicates an excessive thermostat turn back or a mechanical failure that prevented the structure from being heated for a period of time. The difficulty however is that in employing this method for a forensic examination or investigative tool, there are variables that are not accounted for that ultimately undermine the overall credibility of the analysis.
There is therefore a need for a method and system to accurately predict consumption rates in a residential structure. There is a further need for a method and system that can more accurately determine the amount of fuel required to maintain a residential structure at a consistent temperature, thereby allowing identification of various system anomalies that may occur over time. There is still a further need for a method and system that accounts for a number of fuel usage variables such as pilot light and domestic hot water usage in a manner that allows improved accuracy in determining the amount of fuel required to maintain a residential structure at a consistent temperature, thereby allowing identification of various system anomalies that may occur over time.